|
Size: 667
Comment:
|
Size: 1522
Comment:
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 9: | Line 9: |
| '''Default Value''': None |
|
| Line 11: | Line 13: |
| HLen is the header length and is specified as the number of '''32 bit words'''. Thus the header is at most 480 bits (2^4 - 1) * 32. '''Normally this value is '''5''' because we don't specify any options varibles. | HLen is the header length and is specified as the number of '''32 bit words'''. Thus the header is at most 480 bits (2^4 - 1) * 32. '''Default Value''': '''5''', because we don't specify any options varibles. |
| Line 15: | Line 19: |
| This field has had a number of different definitions over the years and is generally used to define the values used on routers etc. '''Default Value''': None |
|
| Line 16: | Line 24: |
This field gives the length of the entire datagram in '''bytes''' rather than words. Thus the '''maximum length''' of a IP datagram is 65535 ----- '''''NOTE: THE NEXT WORD DEAL WITH FRAGMENTATION''''' ----- |
|
| Line 25: | Line 41: |
| The intent is to limit the time (in seconds) a packet can wander around an internet in loops before it is discarded. Since most routers do not synchronize their clocks, each router just decrements the value by one and discards it when it gets to 0. '''Default Value''': 64 |
|
| Line 26: | Line 46: |
This field defines a multiplexing key that determines which higher level protocol to pass the data to. On Linux systems see /etc/protocols. TCP = 6, UDP = 17. |
IPv4 Protocol Notes
http://www.scotnpatti.com/unl/images/ipv4.jpg
Version
Only 4 bits, this field determines the how the rest of the packet is treated
Default Value: None
HLen
HLen is the header length and is specified as the number of 32 bit words. Thus the header is at most 480 bits (2^4 - 1) * 32.
Default Value: 5, because we don't specify any options varibles.
TOS
This field has had a number of different definitions over the years and is generally used to define the values used on routers etc.
Default Value: None
Length
This field gives the length of the entire datagram in bytes rather than words. Thus the maximum length of a IP datagram is 65535
NOTE: THE NEXT WORD DEAL WITH FRAGMENTATION
Ident
Flags
Offset
TTL
The intent is to limit the time (in seconds) a packet can wander around an internet in loops before it is discarded. Since most routers do not synchronize their clocks, each router just decrements the value by one and discards it when it gets to 0.
Default Value: 64
Protocol
This field defines a multiplexing key that determines which higher level protocol to pass the data to. On Linux systems see /etc/protocols. TCP = 6, UDP = 17.
Checksum
SourceAddr
DestinationAddr
Options(Variable)
Pad (Variable)